Ions, including positive ions, are widely used to process electronic devices, optical devices, micro-electromechanical devices (MEMS), as well as to treat materials to alter material properties. Positive ions are readily generated using a variety of apparatus including beamline ion implanters, compact ion apparatus, including plasma immersion devices, and the like.
For high energy implantation, typically 300 kV or greater, tandem acceleration is often used to generate ions of a target energy. Often, tandem acceleration is applied to ions, such as hydrogen ions, in order to generate sufficiently high energy for ions to implant to a desired depth into a substrate. In a tandem acceleration process, an electrostatic accelerator may accelerate negative hydrogen ions generated in an ion source from ground potential up to a positive high-voltage terminal. The electrons on the negative hydrogen ions are then stripped from the negative ion by passage through a charge exchange region, and resulting positive hydrogen ion (proton) is again accelerated as the proton passes to ground potential from the high positive potential. The protons emerge from the tandem accelerator with twice the energy of the high positive voltage applied to the tandem accelerator.
One problem encountered when producing high energy hydrogen ion beams for ion implantation, is the relatively low ion current produced by an ion source generating negative hydrogen ions, placing a limit on throughput of substrates to be implanted with high energy hydrogen. In view of the above, the embodiments of the present disclosure are presented.